DataStax Enterprise does not automatically remove data from nodes that lose part of
their partition range to a newly added node. Run nodetool cleanup
on the source node and on neighboring nodes that shared the same subrange after the
new node is up and running. After adding a new node, run this command to prevent the
database from including the old data to rebalance the load on that node. This
command temporarily increases disk space use proportional to the size of the largest
SSTable and causes Disk I/O to occur.

Important: Failure to run nodetool cleanup after adding a
node may result in data inconsistencies including resurrection of previously deleted
data.